I've built a native application which needs Page Layout info.  You can't call describeLayout directly in Apex, so my workaround is to use a web service callout to call the SOAP API.  It works really well, BUT a few customers are unable to use the app because the call fails due to the describeLayout response being greater than the maximum response size that Apex can digest (3MB).

I have no idea why the response is so larger... the orgs in which I've investigated have a very reasonable number of fields, layouts, record types, etc.

So my questions for you experts:  What the heck is in this response that could be making it so large?  How can I work with the customer to somehow get the response size down?  Any recommendations?